Heart failure is a leading cause of death among all patient populations. This largely reflects the heart's limited ability for self-repair, making cell-based strategies for regenerative cardiac intervention highly attractive. Although many cell types have been examined for this purpose, human embryonic stem (ES) cells or induced pluripotent stem (iPS)cells provide particularly promising and reliable sources of cardiac cells. The overall goal of this project is to elucidate signaling pathways in the development of cardiovascular cells from human ES and iPS cells, from which effective interventional therapies for cardiovascular disease can be derived. Two specific aims are proposed to accomplish our research goals. In Aim 1, we will determine the role of Wnt signaling in the differentiation of human ES and iPS cells into cardiomyocytes, using a panel of cell-type specific markers to estimate the efficiency of cardiac differentiation. In Aim 2, we will study multipotent cardiovascular progenitor cells derived from human ES and iPS cells. These progenitors will be identified by their expression of vascular endothelial growth factor receptor 2 (VEGFR2). We will test the ability of Activin A, BMP4, and Wnt signaling pathways to enhance generation of these progenitors. In addition, we will explore the ability of these cells to differentiate into cardiomyocytes, smooth muscle cells, and endothelial cells in response to Wnt, VEGF and PDGF signaling molecules. From a public health perspective, heart disease is the number one cause of death in the United States and among the most debilitating chronic diseases, despite continuing advances in treatment strategies. We propose a modern approach to examine the role of key signaling molecules in controlling the differentiation of embryonic and induced pluripotent stem cells into functional cardiovascular cells. This will improve our ability to generate cell-based regenerative therapies for heart disease.